Use of cumulative sum (CUSUM) control charts of landed catch in the management of fisheries

Abstract This study examines the use and interpretation of landed catch as an indicator within fisheries management. A monitoring system has been designed to detect trends in time-series of commercial landings. This system was based upon cumulative sum (CUSUM) control charts and tested using simulated data from delay-difference models. Models were parameterised to represent a prawn fishery, a finfish fishery and an elasmobranch fishery. The performance of the scheme was measured by estimating of the probability of true-positive (sensitivity) and true-negative (specificity) outcomes from the signalling scheme. A true-positive outcome occurred when the exploitable biomass had fallen below a reference point and this situation was signalled as out-of-control. On the basis of simulations, the scheme correctly signalled the state of several fisheries with a probability of 60–80%. Sensitivity analyses of the important assumptions within the analysis are presented and examples of how the scheme would be applied to three species with varying life histories are included. Proximate causes of changes in landed catch will always require additional analysis. This scheme should only be used within the systematic prioritisation of stocks that require additional review and assessment. Precautionary management should not be subsumed into the signal detection algorithm but rather be integrated into the review and assessment process.